WO2008056971A1 - Machines de moulage par injection - Google Patents

Machines de moulage par injection Download PDF

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Publication number
WO2008056971A1
WO2008056971A1 PCT/MY2007/000075 MY2007000075W WO2008056971A1 WO 2008056971 A1 WO2008056971 A1 WO 2008056971A1 MY 2007000075 W MY2007000075 W MY 2007000075W WO 2008056971 A1 WO2008056971 A1 WO 2008056971A1
Authority
WO
WIPO (PCT)
Prior art keywords
mould
injection moulding
moulding machine
reservoirs
machine according
Prior art date
Application number
PCT/MY2007/000075
Other languages
English (en)
Inventor
Gregory L. Foster
Original Assignee
Fosterasia Sdn Bhd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fosterasia Sdn Bhd filed Critical Fosterasia Sdn Bhd
Publication of WO2008056971A1 publication Critical patent/WO2008056971A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/02—Transfer moulding, i.e. transferring the required volume of moulding material by a plunger from a "shot" cavity into a mould cavity

Definitions

  • This invention relates to injection moulding machines, and more particularly to multipoint injection moulding machines that can be used for the formation or complicated - shaped mouldings from high viscosity moulding compositions.
  • Injection moulding of shaped products, that cannot be produced, for example, by extrusion or pressure moulding, from thermoplastics materials is a technique that has been used for many years. Molten material is injected into a mould formed of at least two parts and allowed to harden. The mould parts are then separated and the moulding is removed. In cases where the shape is complicated and the molten material has to follow a tortuous flow path it is common practice to use a hot runner plate having various outlet points through which material passes into the mould under high pressure in order that the molten material can flow to all points of the mould before it hardens in the unheated mould. In such a multi-point injection the molten material in the hot runner plate is at the same pressure as the pressure in the extruder, or other device that is feeding the material to the injection moulding machine and is fed into the mould at that pressure.
  • thermoplastic material with a very high filler content such as, the materials filled with vegetable fibres, especially wood fibres, described in WO 00/40384, which have very highly desirable properties and if they could be formed easily into such articles as door and window frames and other similar products that are currently made from timber it would be very beneficial.
  • This invention provides an injection moulding machine that operates very satisfactorily using such materials that are highly viscous when molten although it can also be used with other thermoplastic materials having a lower melt viscosity and which are susceptible to injection moulding using conventional machines.
  • the invention is based on the surprising observation that materials such as wood fibre filled thermoplastic composites when heated to a temperature at which the thermoplastics matrix that binds the wood fibres becomes molten have flow properties, presumably because the molten matrix material acts as a lubricant, and hence the materials can be injected into an injection mould provided that they are injected into the mould at high pressure through multiple injection points arranged such that the material injected through any given injection point only has to travel a short distance through the mould before it meets and coalesces with material injected through one or more other injection points.
  • an injection moulding machine comprises a two part mould, a first part of which has a plurality of injection points through which flowable material can be introduced into the mould, a plurality of reservoirs arranged for receiving a charge of material at a low pressure and subsequently injecting its charge of material through its associated injection point into the mould at a higher pressure, one reservoir being associated with each injection point, the reservoirs being heatable to maintain the temperature of the material above the temperature at which it will flow readily through the mould, means for closing the mould by bringing the two or more mould parts together and means for causing the material to be ejected from the reservoirs into the mould cavity, when the mould has been closed.
  • the reservoirs may be fed from a hot runner plate which receives the moulding material from an extruder or other feed device.
  • a hot runner plate when used, will normally be formed in two parts with the runner channels connecting the individual reservoirs to the incoming feed channel being formed on the surface of one part only but this is only for the sake of economy and • there is no reason why mirror image channels should not be formed in both parts.
  • the material being used in the moulding process will not travel through a runner plate sufficiently readily under the injection pressure to ensure that the requisite amount of material is fed to each of the reservoirs at the correct time and in such cases it may be necessary to modify the runner plate to provide additional means for forcing the material towards the reservoirs.
  • the runner plate may be provided, for example, with flexible screw drives in its channels to force the material towards the reservoirs.
  • the drives may be, for example flexible wire springs that can deflect to allow them follow the curves in the channels in the runner plate.
  • Using individual feeders for the reservoirs has the advantage that when changing the- form of the mouldings to be produced it is not necessary to replace a complicated runner plate but instead it is only necessary to change the positioning of the reservoirs in relation to the injection points of the new mould and to reprogram the robotic feeders. It also allows the machine to be used with multiple moulds, which may be identical or different, and this greatly increases the flexibility of the machine.
  • the reservoirs preferably each comprise a cylinder and a piston
  • the means for causing ejection of the material from the reservoirs comprises a moveable member, such as a plate that impacts on the pistons of all the cylinders simultaneously to force them into their cylinders thereby ejecting at least a part of the molten material therein into the mould over substantially the same period of time. Simultaneous ejection is necessary to ensure that the material in one part of the moulding does not harden before it has bonded with other moulding material flowing in the mould.
  • the cylinder is preferably formed as a bore in the hot runner plate with a restriction at the injection point into the mould ensure that the material from the reservoir is injected under sufficient pressure to flow through the narrowest of the channels in the mould. In such a case the heat for heating the reservoirs is provided by the runner plate.
  • the reservoir may need supplementary heating arrangements.
  • reservoir structures are, for example, a bellows type arrangement or independent screw activators.
  • the main requirement is that at exit from the reservoirs the pressure of the material being ejected is high enough for the material at the injection temperature to flow through the narrowest of channels in the mould and to bond perfectly with a flow of material from another injection point flowing in the opposite direction.
  • vents are, of course, located at the points at which two flows coincide.
  • the. runner plate is fixed and the second mould component is arranged for vertical movement to open and close the mould.
  • the mould parts are brought together using, for example, hydraulic rams or other force applying mechanisms, and the same method may be used in the injection moulding machine of the invention.
  • the forces generated during the injection process in the machine of the invention are very much greater than in a conventional machine and have a tendency to force the two mould parts apart against the hydraulic forces.
  • this two mould parts are preferably positively locked together on closure of the mould, for example, by an automatically operating lock, such as a cam lock, instead of merely being held together using the hydraulics of the machine operating system.
  • the moulding material is preferably fed to the injection moulding machine by an extruder, which may be a single- or multi-screw extruder and which, in addition to melting the material and bringing it to injection temperature, may also be used to mix other components, such as fillers or other compounding ingredients into a basic thermoplastic material.
  • an extruder which may be a single- or multi-screw extruder and which, in addition to melting the material and bringing it to injection temperature, may also be used to mix other components, such as fillers or other compounding ingredients into a basic thermoplastic material.
  • two or more injection moulding machines according to the invention are arranged to be fed by a common feed means so that when one injection moulding machine has been charged and is carrying out its moulding and cooling cycles the feed is switched to the another machine.
  • the feed can be continuous and the non-productive elements of the cycle for one or more machines, for example cooling and discharging are carried out while another machine is carrying out its productive elements.
  • composite articles comprising, for example a material that can only be injection moulded using a machine according to the invention and a rubber, which produces a flexible joint between individual such articles.
  • a flexible strip of a plurality of such articles with adjacent articles being joined by rubber inserts that are firmly bonded to the articles may be achieved by first injection moulding a plurality of spaced apart articles using a first die and then substituting the original die plate by a different die plate and injecting a rubber into the spaces between the individual articles.
  • Such articles as flexible bed slats, which are normally made of plywood can easily be made.
  • Fig. 1 is a vertical section through one form of injection moulding machine according to the invention with the mould, which is for forming a pallet, closes;
  • Fig. 2 is a plan view of the hot runner plate of the injection moulding machine shown in Fig. 1;
  • Fig. 3 is a plan view showing one way of feeding two injection moulding machines from a single feed extruder.
  • the injection moulding machine comprises a frame (10) on which is fixed a hot runner plate (20) for receiving molten moulding material from a feed extruder (not shown).
  • Hot runner plate (20) on its lower surface (30) has one part
  • Mould part (40) has a number of injection points (70) through which molten thermoplastic material can be injected into the mould.
  • Hot runner plate (20 has a number of through bores (80) coaxial with injection points (70), the positions of which are determined to ensure that when molten thermoplastic material injected into the mould formed by bringing parts (40) and (50) together through one injection point (70) flows to a predetermined part of the mould (40, 50) where it meets a second flow from an adjacent injection point (70) both flows are still molten and the material can blend intimately and ultimately bond.
  • Bores (80) form cylinders, which together with pistons (100), form a plurality of reservoirs arranged for receiving a charge of molten material through channels (90) under lower pressure than the pressure in the feed extruder.
  • the piston rods (110) of pistons (10) extend above the upper surface of hot runner plate (20).
  • Pistons (100) can be forced into bores (80) by means of a second slideable platen (120), movement being achieved by means of further hydraulic or pneumatic rams (not shown), which can impact on the protruding ends of piston rods (110) to inject at least a part of the charges of molten material in the reservoirs (80,100) into the mould (40,50).
  • bores (80) are formed as nozzles (130), aligned with, and of the same diameter as, injection points (70), this diameter being reduced compared with the diameter of bores 8, to ensure that material is injected into the mould at a higher pressure than the pressure in reservoirs (80, 100).
  • Locking means which automatically engage when parts (40) and (50) come together, hold the mould closed.
  • two injection moulding machines (140, 150) of the type shown in Figs. 1 to 3, are arranged side-by-side with a feed extruder (160) between them.
  • Extruder (160) is arranged such that it feeds a predetermined charge of material to one of injection moulding machines (140) or (150).
  • a sensor tells the extruder (160) to stop delivery to the first injection moulding machine and to start charging the other machine.
  • the extruder (160) can operate continuously and does not have long down periods while the non-productive parts of the cycle of a single machine are going on.
  • a valve arrangement (not shown) between each machine (140, 150) and extruder (160) is used to switch delivery between the two machines (140, 150).
  • molten material from extruder (160) is forced into hot runner plate (20) where it passes through channels (90) to fill cylinders (8) of the reservoirs, the pistons (100) of which are retracted.
  • the empty mould part (50) is bought together with mould part (40) and the mould (40, 50) is locked closed.
  • platen (130) When the mould has closed platen (130) is lowered to impact on piston rods (110) and force pistons (100) into their cylinders (80) to force the molten material through nozzles (130) into the mould under high pressure.
  • the mould (40, 50) When the mould (40, 50) is full, movement of platen (120) ceases and platen (130) is withdrawn. Lower platen (60) is also withdrawn thereby opening mould (40, 50) to allow removal of the moulded part.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)

Abstract

L'invention concerne une machine de moulage par injection comprenant un moule (40, 50) en deux parties, une première partie de ce moule comprenant une pluralité de points d'injection (70) par lesquels une matière fluide peut être introduite dans le moule (40, 50), une pluralité de réservoirs (80, 100) disposés pour recevoir une charge de matière fondue à basse pression et injecter ensuite cette charge de matière fondue à une pression accrue dans le moule par le point d'injection (70) associé, un réservoir (80, 100) étant associé à chaque point d'injection (70) et les réservoirs (80, 100) pouvant être chauffés pour maintenir la température de la matière fondue au-dessus de la température à laquelle celle-ci s'écoule facilement à travers le moule, des moyens pour fermer le moule par assemblage des parties du moule (40, 50), ainsi que des moyens (130) par l'intermédiaire desquels la matière fondue est expulsée des réservoirs dans la cavité du moule après la fermeture du moule (40, 50).
PCT/MY2007/000075 2006-11-08 2007-11-07 Machines de moulage par injection WO2008056971A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
MYPI20064464A MY177126A (en) 2006-11-08 2006-11-08 Injection moulding machines
MYPI20064464 2006-11-08

Publications (1)

Publication Number Publication Date
WO2008056971A1 true WO2008056971A1 (fr) 2008-05-15

Family

ID=39364736

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/MY2007/000075 WO2008056971A1 (fr) 2006-11-08 2007-11-07 Machines de moulage par injection

Country Status (2)

Country Link
MY (1) MY177126A (fr)
WO (1) WO2008056971A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH711309A1 (fr) * 2015-07-13 2017-01-13 Abi Trading Sàrl Procédé de fabrication d'une palette en bois composite, dispositif pour la mise en œuvre du procédé et moule d'injection pour la réalisation de ladite palette.

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0531925U (ja) * 1991-10-03 1993-04-27 三ツ星ベルト株式会社 マルチノズル用金型装置
US6638049B1 (en) * 1997-06-13 2003-10-28 Synventive Molding Solutions, Inc. Apparatus and method for proportionally controlling fluid delivery to readily replaceable mold inserts
KR20050099124A (ko) * 2004-04-09 2005-10-13 삼성전자주식회사 사출성형장치 및 이를 이용한 사출성형방법
KR20050102461A (ko) * 2004-04-22 2005-10-26 엠앤드엠 주식회사 사출성형기용 역금형

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0531925U (ja) * 1991-10-03 1993-04-27 三ツ星ベルト株式会社 マルチノズル用金型装置
US6638049B1 (en) * 1997-06-13 2003-10-28 Synventive Molding Solutions, Inc. Apparatus and method for proportionally controlling fluid delivery to readily replaceable mold inserts
KR20050099124A (ko) * 2004-04-09 2005-10-13 삼성전자주식회사 사출성형장치 및 이를 이용한 사출성형방법
KR20050102461A (ko) * 2004-04-22 2005-10-26 엠앤드엠 주식회사 사출성형기용 역금형

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH711309A1 (fr) * 2015-07-13 2017-01-13 Abi Trading Sàrl Procédé de fabrication d'une palette en bois composite, dispositif pour la mise en œuvre du procédé et moule d'injection pour la réalisation de ladite palette.

Also Published As

Publication number Publication date
MY177126A (en) 2020-09-07

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